As an example of a power supply system that supplies power to an electronic apparatus through a communication cable, there is a PoE (Power Over Ethernet®) feed system. The PoE feed system is a system that supplies power from PSE (POWER Source Equipment) to a PD (Powered Device) by using a communication cable. The PoE feed system is specified under the standards such as IEEE (Institute of Electrical and Electronic Engineers) 802.3af and IEEE 802.3at.
Patent Literatures 1 to 3 discloses techniques related to a powered device using the PoE feed system. Patent Literature 1 discloses a technique related to a powered device capable of operating even when power used by the load of the powered device itself exceeds the specified value. Patent Literature 2 discloses a technique related to a power transmission system capable of making effective use of limited power. Patent Literature 3 discloses a technique related to a powered device capable of performing a stable operation.